- Start-stop cars need an AGM or EFB battery, not an ordinary lead acid battery, because they withstand far more start cycles.
- AGM is the heavier variant with often a higher CCA. EFB is the lighter, cheaper in-between step.
- An AutoXtreme jump starter does not distinguish between battery types: it delivers current through the clamps, whether the battery is AGM, EFB or ordinary lead acid.
- For the right jump starter always look at the CCA on the battery label, not at the engine type.
If you drive a car with start-stop, there is almost certainly an AGM or EFB battery under the bonnet. Both names sound technical, but the difference is simple to explain. And it becomes relevant the moment you have to jump start it.
What is an AGM battery?
In short: AGM stands for Absorbent Glass Mat. The battery acid is held in a glass fibre mat between the plates, instead of moving freely as in an ordinary lead acid battery. That makes the battery leak proof, shock resistant and suitable for many start cycles in a row.
Cars with a lot of electronics, seat heating or regenerative braking, where the car recovers energy while braking, almost always get an AGM battery from the factory. It is the heaviest and most expensive of the two variants.
What is an EFB battery?
EFB stands for Enhanced Flooded Battery. It is an improved version of the ordinary lead acid battery, with a special coating on the plates and a sturdier casing. As a result an EFB battery can handle more start cycles than a standard battery, but fewer than an AGM. EFB is cheaper and goes into start-stop cars with lighter energy use, such as smaller petrol models without much extra electronics.
What is the difference in CCA?
An AGM battery usually has a higher CCA value, Cold Cranking Amps, the real starting power on a cold start, than an EFB or ordinary lead acid battery of the same size. That is not because AGM is inherently stronger, but because start-stop systems put more strain on the battery: every stop at the traffic light is an extra start cycle. For you as a buyer of a jump starter, this means a start-stop car often needs a higher CCA than you would expect based on the engine size alone. So always check the label on the battery itself. You can read how to do that in reading CCA and EN on your battery label.
How much CCA do you need for a start-stop car?
There is no fixed rule of thumb per engine size, because that depends on the battery type the manufacturer chose. A small petrol car without start-stop often manages with the Boost Mini 3750 (620 CCA). As soon as start-stop and an AGM battery come into play, that CCA figure quickly rises, and the Boost Pro 8250 (960 CCA) is a safer choice. If you drive a larger petrol or diesel engine with AGM and a lot of extra electronics, the Boost Xtreme 8250 (1920 CCA) is the strongest option in the range. The only hard figure that counts is on the label of your own battery.
| Characteristic | AGM battery | EFB battery |
|---|---|---|
| Technology | acid in glass fibre mat, leak proof | improved wet lead acid battery |
| Cycle durability | high | average |
| Typically used in | cars with a lot of electronics, regenerative braking | lighter start-stop models |
| Price | higher | lower |
| CCA level | often higher | average |
Can you jump start an AGM or EFB battery?
Yes, simply. A jump starter from AutoXtreme does not look at the battery type, only at the battery terminals. You connect the smart clamps directly to the battery, red to the positive terminal and black to the negative terminal, wait until 12V Ready appears on the screen and start the car. The only condition is that the CCA of the jump starter is sufficient for the CCA figure on the battery label. If you are not sure what those numbers mean, read what the numbers on a jump starter mean.
Can you simply replace an AGM battery with an EFB, or the other way round?
No, not simply. The car's start-stop system is often specifically tuned to the battery type that originally came with it. If you replace an AGM battery with a cheaper EFB, the system may work less well or the battery may wear out early because of the heavier load. If you want to know for sure which type belongs in your car, check the maintenance manual or ask your garage. This is separate from choosing a jump starter: that works the same on both types.
- Starting power: 960 CCA, more than enough for most AGM and EFB batteries in passenger cars.
- Capacity: 16,000 mAh, good for multiple starts per charge.
- Extras: power bank, flashlight and a 3.7 inch LED screen.
Frequently asked questions
What is the difference between an AGM and an EFB battery?
AGM holds the battery acid in a glass fibre mat and can handle the most start cycles. EFB is an improved lead acid battery: cheaper, but with less cycle durability than AGM.
Does my car have an AGM or EFB battery?
Check the maintenance manual or the label on the battery itself. On AGM batteries this is often stated literally on the casing.
Can I start a start-stop car with an ordinary jump starter?
Yes. An AutoXtreme jump starter does not distinguish between battery types. Just make sure the CCA of the jump starter is sufficient for the battery label.
Why does my start-stop car need a higher CCA?
Start-stop systems start the engine much more often than ordinary driving. The battery is built for that with a higher CCA than you would expect based on engine size alone.
Can I replace an AGM battery with a cheaper EFB battery?
That is not recommended. The start-stop system is tuned to the original battery type, and a lighter battery may wear out faster or cause the system to fail.
